J/AJ/156/223 Observations of the main-belt comets 238P & 288P (Hsieh+, 2018)
The 2016 reactivations of the main-belt comets 238P/Read and
288p/(300163) 2006 VW139.
Hsieh H.H., Ishiguro M., Kim Y., Knight M.M., Lin Z.-Y., Micheli M.,
Moskovitz N.A., Sheppard S.S., Thirouin A., Trujillo C.A.
<Astron. J., 156, 223-223 (2018)>
=2018AJ....156..223H 2018AJ....156..223H (SIMBAD/NED BibCode)
ADC_Keywords: Solar system ; Comets ; Photometry ; Optical
Keywords: comets: general - comets: individual: (238P, 288P) -
minor planets, asteroids: general
Abstract:
We report observations of the reactivations of the main-belt comets (MBCs)
238P/Read and 288P/(300163) 2006 VW139 that also track the evolution
of each object's activity over several months in 2016 and 2017. We
additionally identify and analyze archival SDSS data showing 288P to have
been active in 2000, meaning that both 238P and 288P have now each been
confirmed to be active near perihelion on three separate occasions. From
data obtained of 288P from 2012-2015 when it appeared inactive, we find
best-fit R-band H, G phase function parameters of HR=16.80±0.12 mag
and GR=0.18±0.11, corresponding to effective component radii of
rc=0.80±0.04 km, assuming a binary system with equally sized
components. Fitting linear functions to ejected dust masses inferred
for 238P and 288P soon after their observed reactivations in 2016, we
find an initial average net dust production rate of Md=0.7±0.3 kg/s
and a best-fit start date of 2016 March 11 (when the object was at a true
anomaly of ν=-63°) for 238P, and an initial average net dust
production rate of Md=5.6±0.7 kg/s and a best-fit start date of
2016 August 5 (when the object was at ν=-27°) for 288P. Applying
similar analyses to archival data, we find similar start points for
previous active episodes for both objects, suggesting that minimal mantle
growth or ice recession occurred between the active episodes in question.
Some changes in dust production rates between active episodes are detected,
however. More detailed dust modeling is suggested to further clarify
the process of activity evolution in MBCs.
Description:
Observations of 238P and 288P presented here were obtained with the
8.1 m Gemini North (Gemini-N) telescope, the 3.54 m Canada-France-Hawaii
Telescope (CFHT), and the University of Hawaii (UH) 2.2 m telescope on
Maunakea in Hawaii, the 8.1 m Gemini South (Gemini-S) telescope at Cerro
Pachon in Chile, the 6.5 m Baade Magellan telescope at Las Campanas in
Chile, Lowell Observatory's 4.3 m Discovery Channel Telescope (DCT) at
Happy Jack, Arizona, the 2.5 m Sloan Digital Sky Survey (SDSS) telescope
at Apache Point Observatory in New Mexico, and the Lulin One-meter
Telescope (LOT) at Lulin Observatory in Taiwan. We employed the Gemini
Multi-Object Spectrographs (GMOS; Hook et al. 2004PASP..116..425H 2004PASP..116..425H;
Gimeno et al. 2016SPIE.9908E..2SG) and Sloan r'-band filters for Gemini-N
and Gemini-S observations, MegaCam (Boulade et al. 2003SPIE.4841...72B 2003SPIE.4841...72B)
and a Sloan r'-band filter for CFHT observations, a 2048x2048 pixel
Textronix CCD and a Kron-Cousins R-band filter for UH 2.2 m observations,
the Inamori Magellan Areal Camera and Spectrograph (IMACS; Dressler et al.
2011PASP..123..288D 2011PASP..123..288D) and a Sloan r'-band filter for Baade observations,
the Large Monolithic Imager (Bida et al. 2014SPIE.9147E..2NB) and a
Kron-Cousins R-band filter for DCT observations, and a VersArray:1300B
CCD (Kinoshita et al. 2005ChJAA...5..315K 2005ChJAA...5..315K) and a Bessell-like R-band filter
for LOT observations. SDSS data presented here were obtained using a
large-format mosaic CCD camera designed for the SDSS survey (Gunn et al.
1998AJ....116.3040G 1998AJ....116.3040G) and a Sloan r'-band filter.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 121 24 Observation log: 238P - active
table2.dat 121 16 *Previously reported observations of 238P
when active
table3.dat 121 30 Observation log: 288P - active
table4.dat 121 20 Observation log: 288P - inactive
table5.dat 121 15 *Previously reported observations of 288P
when active
--------------------------------------------------------------------------------
Note on table2.dat: All 2005 data from Hsieh et al. (2009AJ....137..157H 2009AJ....137..157H), and
all 2010 data from Hsieh et al. (2011ApJ...736L..18H 2011ApJ...736L..18H).
Note on table5.dat: All data from Hsieh et al. (2012ApJ...748L..15H 2012ApJ...748L..15H).
--------------------------------------------------------------------------------
See also:
J/A+A/505/1297 : Hawaii Trails Project (Hsieh, 2009)
Byte-by-byte Description of file: table[12345].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 "date" Date UT date of observation
13- 22 A10 --- Tel Telescope used (1)
24- 25 I2 --- Nexp [1/35]? Number of exposures (not in Tables 2,5)
27- 30 I4 s Tint [54/7200]? Total integration time (not in
Tables 2,5)
32- 33 A2 --- Filt [R r'] Filter (not in Tables 2,5)
35- 40 F6.1 deg v [-125/140.2] True anomaly ν
42- 46 F5.3 AU HDist [2.361/3.458] Heliocentric distance
48- 52 F5.3 AU GDist [1.368/3.566] Geocentric distance
54- 57 F4.1 deg alpha [0.5/25.2] Solar phase angle (Sun-object-Earth)
α
59- 63 F5.2 mag Rmag [18.6/23.2]? Equivalent mean apparent R-band
nucleus magnitude, measured within photometry
apertures with radii of 4.0"
65- 68 F4.2 mag e_Rmag [0.02/0.14]? Uncertainty in Rmag
70 A1 --- l_RmagT [<] Limit flag on RmagT
71- 74 F4.1 mag RmagT [18.6/22.3]? Equivalent total mean apparent
R-band magnitude, including the entire coma
and tail, if present
76- 78 F3.1 mag e_RmagT [0.1]? Uncertainty in RmagT (not in Tables 2,5)
80 A1 --- l_RMag [<] Limit flag on RMag (not in Table 4)
81- 84 F4.1 mag RMag [14.6/18.3]? Total absolute R-band magnitude,
using the H, G phase function (not in Table 4)
(2)
86- 88 F3.1 mag e_RMag [0.1/0.2]? Uncertainty in RMag (not in
Tables 2,4,5)
90 A1 --- l_Mdust [>] Limit flag on Mdust (not in Table 4)
91- 95 E5.2 kg Mdust [2e+06/8.7e+07]? Estimated total dust mass,
assuming ρd∼2500 kg/m3 (not in Table 4)
97-101 E5.2 kg e_Mdust [1e+06/2e+07]? Uncertainty in Mdust (not in
Table 4)
103-106 F4.1 cm Afrho [1/14.7]? Afρ value computed using
photometry apertures with radii of 4.0" where
uncertainties are estimated to be ∼10%
(not in Tables 2,4,5)
108-110 F3.1 cm e_Afrho [0.1/2.9]? Uncertainty in Afrho (not in
Tables 2,4,5)
112-116 F5.2 mag RmagR [16.84/18.09]? Estimated reduced R-band
magnitude at the midpoint of the full
photometric range (assumed to be 0.80 mag) of
the rotational light curve (only in Table 4)
118-121 F4.2 mag e_RmagR [0.05/0.4]? Uncertainty in RmagR (only in
Table 4)
--------------------------------------------------------------------------------
Note (1): Telescope as follows:
UH 2.2 = UH 2.2 m telescope;
NTT = New Technology Telescope;
Keck = Keck I Observatory;
PS1 = Pan-STARRS1;
FTN = Faulkes Telescope North;
Perkins = Lowell Observatory Perkins Telescope;
HCT = Himalayan Chandra Telescope;
WHT = William Herschel Telescope;
LOT = Lulin One-meter Telescope;
CFHT = Canada-France-Hawaii Telescope;
Gemini-N = Gemini North telescope;
Gemini-S = Gemini South telescope;
SDSS = Sloan Digital Sky Survey telescope;
Magellan = Magellan Baade telescope;
DCT = Discovery Channel Telescope.
Note (2): In Tables 1 and 2: where G=-0.03,
In Table 3: where G=0.18,
In Table 5: at R=Δ=1 AU and α=0°, using IAU H, G
phase-darkening, where G=0.18.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Tiphaine Pouvreau [CDS] 08-Apr-2019